Pixelated devices have become staples of modern-day living. At present, among the most common of such devices are flat panel displays (e.g., liquid crystal and/or active matrix organic light emitting diode (OLED)), which utilize local pixel electrodes to control individual pixels.
For example, a liquid crystal display (LCD) is structured having liquid crystal material injected between two substrates. When voltages of different potentials are applied to electrodes on the substrates to form electric fields, the alignment of liquid crystal molecules of the liquid crystal material is varied and, accordingly, the transmittance of incident light is controlled to enable the display of images.
More specifically, formed on one of the substrates is wiring, which is electrically connected to each pixel and which defines pixels in a matrix arrangement by transmitting image signals and scanning signals. Pads are connected to ends of this wiring, and are used as a means to transmit the image signals and scanning signals to the wiring from an external drive circuit. To prevent damage to the pads, it is preferable to cover the pads with conductive auxiliary pads. Additionally, in active matrix LCDs, thin film transistors (TFTs) for discontinuing the transmittance of the image signals, and pixel electrodes for transmitting the image signals are formed on this substrate, referred to as a TFT substrate.
In LCDs and many other pixilated device applications, pixel electrodes must be transparent to allow transmission of incident light. Currently, the most common transparent electrode materials are transparent conducting oxides (TCOs), specifically indium-tin-oxide (ITO). Unfortunately, ITO can be an inadequate solution for many device applications (e.g., due to its relatively brittle nature and correspondingly inferior flexibility and abrasion resistance). Additionally, fabrication of ITO components on non-flat surfaces (e.g., TFT substrates) can be extremely challenging with respect to patterning, adhesion and step-coverage. Furthermore, the indium component of ITO is rapidly becoming a scarce commodity, and ITO deposition usually requires expensive, high-temperature sputtering, which can be incompatible with many device processes.